A band saw machine is used extensively for cutting a workpiece made of metal. As a cutting tool of a band saw blade, used is a Bi-Metal saw blade made by attaching teeth made of high speed steel, cemented carbide and so on to a blade body made of high ductility spring steel.
In addition, also used is a variable-pitch saw blade, in which pitches of its teeth are varied in order to reduce cutting noises. Further, also used in practical is a saw blade with kerf dispersed type tooth profile, which makes cut chips fine by making a set width wider as a tooth height (a length from a reference position to a tooth tip) becomes lower.
A band saw machine is also used for cutting a structural steel such as an I-beam. Especially, when cutting a large structural steel, there may be a case where cutting becomes impossible because a cut slit becomes narrow during cutting and then a saw blade gets stuck in the structural steel.
In order to prevent such a problem, a saw blade that makes a width of a cut slit wider by setting a set width wider is used in practice. In addition, there may be a case where cut surfaces become rough when a set width is wide (especially, cut surfaces become significantly rough when a set width reaches almost a half of a blade thickness). In order to improve such a disadvantage, there exists a saw blade having two types of set widths, narrow and wide.
As a saw blade with kerf dispersed type tooth profile mentioned above, there is a saw blade that was made by the present applicant and disclosed in a Patent Document 1 (Japanese Granted Patent No. 4301806) listed below.
FIG. 5(a) to FIG. 5(c) shows a saw blade 29 disclosed in the third embodiment of the Patent Document 1. As shown in FIG. 5(a) and FIG. 5(b), the saw blade 29 has, successively from right, a first group 33(A1) composed of a straight tooth S1 and three (the odd number of) set teeth, and a second group 31(A2) composed of a straight tooth S2 and two (the even number of) set teeth. In addition, a main group 35(A) is configured of the first group 33(A1) and the second group 31(A2). Further, a main group 35(B) composed of a first group 33(B1) and a second group 31(B2) comes next to the main group 35(A). Set-bending sides (R-side or L-side) of the teeth in the main group 35(B) are made opposite to set-bending sides of the teeth in the main group 35(A), respectively. In this manner, it is configured by arranging the main group 35(A) and the main group 35(B) alternately and repeatedly.
In addition, tooth heights of all the teeth in the first group 33 are almost identical (Hi). Similarly, tooth heights of all the teeth in the second group 31 are almost identical (Lo). In FIG. 5(b), Hi means that a tooth height is high, and Lo means that a tooth height is low.
In addition, Lw or Rw is a wide set tooth, and Ln or Rn is a narrow set tooth. For example, Rw1, Rw2 and Rw3 are set teeth all are bent to an identical side and have an identical width, and perceived as identically-functional teeth.